Title
Non-Adiabatic Reaction Dynamics
Date & Time: Thursday 18th January, 2018 at 4.00 PM
Venue: SSCU AUDITORIUM
Abstract:
In case of both electronic transition and electron transfer reaction, adiabaticity and non-adiabaticity of potential energy surfaces play a significant role in controlling the rate, even the course of the chemical processes. When the coupling between two states of a system is large, it is said to be adiabatic states, otherwise diabatic (or non-adiabatic). A large number of important chemical and biological processes involve non-adiabatic reactions which makes this field appealing to physical chemists, biologists, material scientists and many more [1]

Marcus theory provides the foundation for understanding electron transfer reactions which is based on non-adiabatic model[3]. On the other hand, molecular Quantum mechanics, used to study electronic transitions of molecules, is dominated by Born-Oppenheimer (B-O) approximation. When two or more potential energy surfaces come close together, B-O approximation breaks down and non-adiabatic reactions enter into the reaction pathway. A large number of theories, computational methods have been proposed to study such non-adiabatic transitions. Further, recently, an experiment has been carried out, successfully for real time observation of non-adiabatic transition.

In this talk, at first, adiabatic and non-adiabatic transitions will be described, then electron transfer reaction will be discussed with the help of Marcus’s theory. Next, I shall explain non-crossing rule and conical intersection for non-adiabatic electronic transition, why B-O approximation fails to describe non-adiabatic electronic transition and introduce some popular semi-classical methods such as Landau-Zener, Ehrenfest Method and surface hopping technique[4,5,6]. Next, I will conclude my talk with the application of surface hopping method to the photochemistry of DNA nucleobases and the recent experimental observation of non-adiabatic dynamics to achive both spatial and temporal characterization of conical intersections.